Pipe bombs had been mailed to several targets along the US east coast, including a former president and secretary of state. Sirens were wailing and emergency vehicles were racing through midtown Manhattan in a troubling echo of previous terror attacks.
It was a moment for national unity. Except it wasn’t.
In the hours that followed, political leaders mouthed the usual platitudes about “coming together” and refusing to be terrorised. But to greater and lesser degrees, they also suggested where they believed responsibility lay: with their opponents.
New York Mayor Bill de Blasio, standing outside the Manhattan offices of CNN — one recipient of a suspected bomb — at first followed the script for such occasions, praising law enforcement and insisting New Yorkers would go about their business.
But then the Democratic mayor departed from it, suggesting there was a direct line between the attack and Republican President Donald Trump’s inflammatory rhetoric.
“Unfortunately, an atmosphere of hatred is contributing to the choices people are making to turn to violence. There’s no question about it,” Mr de Blasio said, even though the investigation had only just begun. It was incumbent on politicians to lower the temperature, he added, “and that has to start at the top”.
Hours later, at a campaign rally in Wisconsin, Mr Trump pushed back, blaming the news media for the nation’s tense climate.
“The media also has a responsibility to set a civil tone, and to stop the endless hostility and constant negative — and oftentimes false — attacks and stories,” he told an approving audience.
As the crisis deepened on Thursday, with the discovery of additional bombs, so did the president’s pique with the news media.
“A very big part of the Anger we see today in our society is caused by the purposely false and inaccurate reporting of the Mainstream Media that I refer to as Fake News,” Mr Trump wrote in a tweet. “It has gotten so bad and hateful that it is beyond description. Mainstream Media must clean up its act, FAST!”
So began a new chapter in how a polarised land deals with national emergencies. Events that once inspired national unity and gestures of conciliation instead appeared to be deepening suspicions and reinforcing divisions.
“We have entered a new era where everything is perceived through the lens of partisanship,” said Keena Lipsitz, a political scientist at Queens College, who struggled to recall another terror threat that had prompted a similar reaction.
Like Mr de Blasio, one side appeared convinced there was a link between the bombs and the president’s rhetoric, she said, while the other faulted the media — or dismissed the entire episode as a fake. “Nothing is taken at face value any more,” Ms Lipsitz said.
The rancour was likely amplified by a harsh political season that featured an unusually bruising Supreme Court confirmation hearing for judge Brett Kavanaugh and will culminate in midterm elections next month that many have come to regard as a referendum on a polarising president.
It flowed almost immediately. Soon after the White House spokesperson tweeted her condemnation on Wednesday morning of attempted attacks against ex-president Barack Obama, former secretary of state Hillary Clinton and “other public figures”, CNN presenters took umbrage that their network had not also been acknowledged as a victim.
“To say nothing about the fact that CNN was targeted?” presenter David Gregory fumed live on air. “That is outrageous from an administration and from a president that specifically targets and attacks CNN.”
Later Jeff Zucker, CNN Worldwide’s president, blasted Mr Trump for failing to appreciate the hostility he had whipped up with repeated attacks on the press — including his praise last week for a congressman who assaulted a reporter.
“The president, and especially the White House press secretary, should understand their words matter,” Mr Zucker said in a statement. “Thus far, they have shown no comprehension of that.”
Previous terror attacks have served to elevate US political leaders, Mitchell Moss, a professor at New York University, observed, noting Bill Clinton’s healing performance after the bombing of a federal building in Oklahoma City and George W Bush’s show of determination amid the wreckage of the World Trade Center.
The latest episode was different, Mr Moss acknowledged, because it had caused no fatalities. It was also directed entirely at the president’s critics — from Mr Obama and Mrs Clinton to CNN and, on Thursday, the actor Robert De Niro, among others.
“The Trump style of personal attack has now become part of the American political scene,” Mr Moss said. “The bombs may not be due to Trump but the fact that the people he identified over the past month were all targeted is not coincidental.”
By chance, Arizona’s outgoing Senator Jeff Flake, who spent much of Mr Kavanaugh’s hearing bemoaning the crumbling of civility in national politics, appeared outside CNN on Wednesday, gawking over the police cordon along with a throng of tourists and curious New Yorkers. He had been in the neighbourhood for an appointment when he noticed the disturbance. For a time, he went unrecognised.
“Obviously, it’s horrible,” Mr Flake said, after a reporter approached him. Although a vocal Republican critic of Mr Trump, he refused on this occasion to condemn the president for deepening the nation’s divide. “Well, obviously, some people are worked up on both sides,” Mr Flake said, looking glum.
Whatever investigators eventually turn up, Mrs Lipsitz, the professor, predicted that partisans on both sides would find ways to justify their views — and that nothing good would come of it. She put little stock in calls for unity.
“What political leaders usually mean when they call for unity is that the other side should ‘shut up’,” she said.
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